[Ovmsdev] RAM

[Mark Webb-Johnson]

With our default menuconfig (plus memory debugging enabled), I get:

I (0) cpu_start: App cpu up.
I (2206) heap_alloc_caps: Initializing. RAM available for dynamic allocation:
I (2229) heap_alloc_caps: At 3FFAFF10 len 000000F0 (0 KiB): DRAM
I (2249) heap_alloc_caps: At 3FFCA290 len 00015D70 (87 KiB): DRAM
I (2270) heap_alloc_caps: At 3FFE0440 len 00003BC0 (14 KiB): D/IRAM
I (2291) heap_alloc_caps: At 3FFE4350 len 0001BCB0 (111 KiB): D/IRAM
I (2313) heap_alloc_caps: At 400955AC len 0000AA54 (42 KiB): IRAM

OVMS > module memory
============================
Free 8-bit 77696/218088, 32-bit 18608/43580, numafter = 872
task=Asy total=      0      0  24972 change=     +0     +0 +24972
task=tiT total=    352      0      0 change=   +352     +0     +0
task=Hou total=  20192  24444      0 change= +20192 +24444     +0
task=mai total=   9488  26948      0 change=  +9488 +26948     +0
task=IDL total=     72      0      0 change=    +72     +0     +0
task=ipc total=   9320      0      0 change=  +9320     +0     +0
task=eve total=  41440      0      0 change= +41440     +0     +0

If I turn off bluetooth in menuconfig, I get:

OVMS > module memory
============================
Free 8-bit 150548/290912, 32-bit 18628/43600, numafter = 872
task=Asy total=      0      0  24972 change=     +0     +0 +24972
task=tiT total=    352      0      0 change=   +352     +0     +0
task=Hou total=  44592      0      0 change= +44592     +0     +0
task=mai total=  36436      0      0 change= +36436     +0     +0
task=IDL total=     72      0      0 change=    +72     +0     +0
task=ipc total=   9320      0      0 change=  +9320     +0     +0
task=eve total=  41468      0      0 change= +41468     +0     +0

72KB RAM seems a bit ridiculous for a bluetooth stack. I really hope this is not Espressif loading those binary blobs from libbtdm_app.a into RAM.

If I configure a minimal (for our needs) bluetooth (BLE only), I get:

 --- Bluedroid Bluetooth stack enabled
(3072) Bluetooth event (callback to application) task stack size (NEW)
[ ]   Bluedroid memory debug (NEW)
[ ]   Classic Bluetooth (NEW)
[*]   Release DRAM from Classic BT controller
[*]   Include GATT server module(GATTS) (NEW)
[ ]   Include GATT client module(GATTC)
[*]   Include BLE security module(SMP) (NEW)
[*]   Close the bluedroid bt stack log print (NEW)
(2)   BT/BLE MAX ACL CONNECTIONS(1~7) (NEW)

OVMS > module memory
============================
Free 8-bit 106312/246720, 32-bit 18576/43548, numafter = 872
task=Asy total=      0      0  24972 change=     +0     +0 +24972
task=tiT total=    352      0      0 change=   +352     +0     +0
task=Hou total=  21840  22776      0 change= +21840 +22776     +0
task=mai total=  36436      0      0 change= +36436     +0     +0
task=IDL total=     72      0      0 change=    +72     +0     +0
task=ipc total=   9320      0      0 change=  +9320     +0     +0
task=eve total=  41476      0      0 change= +41476     +0     +0

With just classic bluetooth enabled:

OVMS > module memory
============================
Free 8-bit 77696/218096, 32-bit 18608/43580, numafter = 872
task=Asy total=      0      0  24972 change=     +0     +0 +24972
task=tiT total=    352      0      0 change=   +352     +0     +0
task=Hou total=  20200  24444      0 change= +20200 +24444     +0
task=mai total=   9488  26948      0 change=  +9488 +26948     +0
task=IDL total=     72      0      0 change=    +72     +0     +0
task=ipc total=   9320      0      0 change=  +9320     +0     +0
task=eve total=  41440      0      0 change= +41440     +0     +0

Turning off our memory and task debugging features, and enabling BLE GATT server + security (2 connections), gives me 122KB in metric m.freeram. That should include bluetooth requirements, but no wifi running yet. With wifi, it drops to 82KB. That should be what end-users of OVMS will see, and I’m happy with that, so have committed that as a default config for the moment.

With memory and stack debugging enabled (as developers will most likely use), it drops 122KB-> 106KB.

I did see some comments in the forums about this. For example:

https://www.esp32.com/viewtopic.php?t=3139 <https://www.esp32.com/viewtopic.php?t=3139>

It seems that IDF 3.0 changes the way this works (dynamic, rather than static as per menuconfig), and in the documentation for that they mention 70KB. It looks like a minimal bluetooth for us is going to cost 40KB RAM or so.

Regards, Mark.

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